Researches in the field of life sciences are based on the analysis of biological materials or samples, mineral substances or chemical substances. Among them, biological materials or samples include samples from animal body surface or body fluid, such as oral scraps, saliva, sputum, blood and urine; nucleic acid samples, such as genomic DNA, PCR products, cloned DNA and RNA; protein samples, such as enzymes and polypeptides; microorganisms, including prokaryotes, such as bacteria, archaebacteria, viruses (e.g., bacteriophage, prion); eukaryotes, such as protozoan, and fungi (e.g., yeasts); lower plants, such as algae; advanced plants and animal samples, including various cells, such as somatic cells, stem cells, germ cells (sperm cells and egg cells), and various tissue samples, etc.
Biological samples are most frequently placed and stored in devices contained with liquid medium or a buffer solution, and they require storage at such subzero temperature (e.g., −20° C. or −70° C.˜−80° C.). In some cases, samples have to be dried first, and then are stored at room temperature (WO 2005/113147, US 2005/0276728, US 2006/0099567), or 4° C., or −20° C., or −70˜−80° C. However, the highly labile nature of biological samples makes it extremely difficult to preserve their biological activity over extended time periods. Although lyophilization of nucleic acid and protein samples can extend the storage life, the subsequent loss of activity upon reconstitution in a liquid makes lyophilization a less than ideal storage technique.
In addition to storage, biological samples generally need to be transported. In transportation of biological samples, ice, dry ice or other refrigerating equipment can be used to provide a freezing environment. However, when the time for transportation is too long, for example, international transportation or even intercontinental transportation, and especially when the refrigerating equipment and energy are deficient, it is not that easy to obtain a low-temperature or even freezing environment.
Therefore, when collecting biological samples, particularly collecting samples from a large population over vast territory, if a room-temperature storage method without expansive refrigerating equipment can be used, while integrity and stability of samples can be retained to the largest extent for a long time, thereby reducing the effects on the subsequent analysis, it will hold an enormous advantage.